Despite there being a police detective investigating the case, I felt that the real protagonist of this novel was Dr. John Archer before I knew that author Rudolph Fisher was a physician. I thought that Dr. Archer was the best developed and most sympathetic character. Rudolph Fisher's background also explains why the medical details seemed so authentic.
The Conjure Man, Frimbo, was a highly ambivalent character. This ambivalence caused me to wonder if his background was falsified. Was he really an African king or a graduate of Harvard University? We only have Frimbo's word for it. He was clearly a very intelligent man. I read an interesting academic article by Adrienne Gosselin about The Conjure Man Dies which compares Frimbo to the Egyptian God, Osiris. There are certainly some parallels to the story of Osiris in this book, but I would also identify Frimbo with the African trickster deity, Anansi, because he seemed to me a master of deception. Due to Frimbo's acts of misdirection, most of this novel deals with figuring out what was done rather than whodunit.
The mystery is cleverly constructed with a number of plot twists that are surprising. The most surprising development had me exclaiming, "What just happened here?" It caused me to entertain the notion that Frimbo could have been a genuine practitioner. Some of the stories told about him sounded like he had real powers of sorcery, but he behaved too much like an illusionist for me to surrender my doubts about him. In the end, I disliked his arrogance and tendency toward duplicity.
The Conjure Man Dies has been criticized for its Amos and Andy type of dialogue that seems so dated today. I confess that I wasn't enamored with that dialogue either. It made most of the characters seem like caricatures.
So there were aspects of the book that I liked, and it certainly held my interest. Yet my feelings about Frimbo and the dialogue lowered it in my estimation.